Li-ion batteries in portable electronic devices typically undergo different charging, discharging and storage routines based on their use. Batteries that employ Li-ion cell chemistry may produce gas when they are improperly charged, shorted or exposed to high temperatures. This gas can be combustible and may compromise the reliability and safety of such batteries. A current interrupt device (CID) is typically employed to provide protection against any excessive internal pressure increase in a battery by interrupting the current path from the battery when pressure inside the battery is greater than a predetermined value.
However, even in the absence of excessive internal pressure that would diminish performance or cause safety concerns, li-ion batteries undergo increased internal pressure during recharging. In prismatic cells, increased internal pressure causes the cell casing to flex. Depending upon the makeup and amount of electrode and electrolyte material within a cell casing, such as a 183665 prismatic cell casing, an outside diameter of about 18.02 mm can increase during recharging by over one millimeter, to about 19.5 mm. Use requirements of many battery types, including prismatic cells, often limit the space available for expansion during charge cycles, thereby restricting the types of batteries employed, their capacity, or the patterns of their use (e.g., removal from devices during charging).
Therefore, a need exists for a cell casing that significantly reduces or eliminates the above-mentioned problems.